The technique of including a wheel in a computer input device such as mouse or keyboard is known in the art. For instance, U.S. Pat. No. 6,700,564 of Microsoft Co. and U.S. patent publication No. 2003/0025673 A1 disclose an input device equipped with a rotary wheel. When users browse documents on the screen of a computer, they can move the wheel with fingers to change pages, scroll text contents or perform document editing operations. It is especially handy for users to do document browsing, Web searching or image zooming operation. There is no need to maneuver the PAGE DOWN/UP keys on the keyboard or the scroll bar on the screen through the mouse. Through the wheel on the input device, scroll of text pages or lines can be done easily.
However, the conventional wheel structure is complex and bulky. Fabrication and assembly are difficult. Production cost is higher. To shrink the size of electronic products that include the wheel input device is not easy. This makes conforming to the prevailing trend of thin and light difficult.